Sound absorbing structure



Agg. 22, 1944. HANNs-HElNz' wou-'F SOUND AYBSORBING STRUCTURE Filed Nov. 5, 1941 4 Sheets-Sheet 1 ILM;

A118 22,1944- HANNs-HEINZ woLFF 2,356,640

SOUND ABSORBING STRUCTURE Filed Nov. 52,1941 4 'sheets-sheet 2 Fig. 3

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'SOUND ABSORBING STRUCTURE Filed Nov. 3. 1941 4 Sheets-Sheet 3 /n venfor':

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Patented Aug. 22, 1944 2.35am SOUND lAnsomzluo STRUCTURE Hanns-Heinz Wolt, Berlin, Germany; vested in the Alien Property Custodian Application November s, 1941, serial No. 417,671 In Germany September 17, 1940 (Ci. Zit-4) 6 Claims.

The present invention relates to sound absorbing structures applicable to, er usable as, wells rooms, such as laboratories for acoustic experiments, broadoastor sound-hlm studios and the like, and adapted to prevent air oscillations produced within the room or, more gein erally, at the side of the structure, from being reflected thereby, and, preferably, also from penetrating therethrough. The general term walL in this connection, is intended to comprise not only the side Walls but also the ceiling and the :door of a room.

It is the object oi the present invention to improve the sound absorbing properties of a structure having a prescribed absorption coefficient. while reducing the space required therefor in prior art structures.

According to the invention, at least a part of the outer face of a sound absorbing structure made of sound absorbing material is cornn posed of a plurality of tapering elements, and the elements are arranged in at least two groups, the tops of the elements of each `group lying in surfaces substantially parallel but displaced with respect to one another in the direction of the axes of the elements.

In a preferred embodiment of the invention the tapering elements have the shape of pyra-v raids, but it should be kept in mind that cones to be considered as substantially equivalent to pyramids.

Further, the surfaces dened by the tops of the pyramids will ordinarily be parallel to the surfaces formed by the bases of the pyramids, but the case may be that the bases of pyramids, the tops of which lie in one and the same surface, do not lie all on the same level.

The term parallel surfaces, in connection with this invention, should be understood to comprise also, for example, the surfaces of concentric cylinders, and, more generally, all surfaces, the homologous points of which have equa'l distances from one another.

` The invention will be more fully understood with the aid of, and further features of the invention will be apparent from,'the following more detailed description and the accompanying drawings. In the drawings, in a purely diagrammatic fashion and by way of example,

Figs. 1 and 2 illustrate a. fragmentary vertical `section and a corresponding ground plan, re-

spectively, of a. sound absorbing structure according to the invention, the view of Fig. 1 being taken from the plane I--I of Fig.2. According to this embodiment of the invention, the sound absorbing structure is composed of a plurality of equal' bodies having square bases, two groups ci bodies being arranged one above the other.

Figs. 3 and 4, in a manner similar to that of Figs. i and 2, show a sound absorbing structure composed of bodies having triangular bases, Fig. Zi being taken substantially on the line 3 3 of Fig. 4. y

Figs. 5 and 6 similarly represent a modification of the invention where the size of the bodies belonging to the one group is different from the size of the bodies belonging to the other group, Fig. 5 being taken substantially on the line 5--5 of Fig. 6.

Fig. diagrammatically illustrates a modiiication where the side faces of the pyramidic portions are concave.

Figs. 8 'and 9, illustrate in vertical section and `iront view respectively a modification wherein solid pyrainidic bodies are arranged on the two opposite sides of the structure which may be used as a sound separating wall, Fig. 8 being taken substantially on the line 8-8 of Fig. 9.

Figs. lll and ll similarly show a modification of `an arrangement substantially according to Figs. 8 and 9, the sound absorbing structure being composed of hollow bodies, and Fig. 10 being taken substantially on the line IIL-I0 of Fig. 11.

Fig. 12 represents a frame work for supportvlng an arrangement substantially according to Figs. 10 and 11.

According to Fig. 1, the sound absorbing structure is composed of a plurality of elementary bodies of equal size which are .made of sound deadening material. 'Ihe bodies have the shape of pyramids and are arranged in two groups I and 2, one behind (or above) the other. 'The elementary bodies of the one group are displaced with respect to theA elementary bodies of the other groups in the direction of the axes of the pyramids to such an extent that the plane surface formed by the bases of the pyramids of group I substantially coincides with the'plane .surface dened by the tops of the pyramids of groupY 2.

Further, the groups are so mounted wlthrespect to one another that the sound energy still penetrating through the rst group is ab- 'sorbed by the second, the arrangement being preferably such that the sound energy, which is still reflected by the second group is absorbed by` Y.

the rearside oi the rst.

For this purpose, as may be seen from Figs.

1 4, the-rst group is so mounted that the single sound absorbing bodies are not arranged closely side by side, but that free spaces are left between them, through which the sound is guided into the second sound absorbing set.

Thus the ediciency of the structure is greatly increased and, of course, the more, the smaller is the angle at the top of the tapering elementary bodies, and the larger isfthe number of groups or sets.

The reference numeral i denotes the sound absorbing bodies of the first group or set, the reference numeral 2 those of the sound group or set, and by 3 is denoted a base (or outside) layer which preferably is also made of sound absorbing material.

The fastening of the sound `absorbing bodies 2 to the base iayer 3 does not create any diiliculty. Between the sound absorbing bodies i and the sound absorbing bodies 2 there is mounted a wire net 4 which, on the one hand, supports the sound guiding bodies l and, on the other hand, if suitably designed, may be used for holding the tops of the bodies 2 in their correct position. The tops of the sound absorbing bodies i may be nxed, if required, by a wire net 5.

In the arrangement illustrated by Figs. i and Y2 the sound absorbing bodies have substantially quadratic bases.

The arrangement according to Figs. 3 and 4 is quite similar to that illustrated by Figs. l and 2, but is modified insofar as the bases ci the pyramids have the shape o (equilaterali triangles. the line 3--3 0;" Fig. e, and the same reference numerals are used as in Figs. l and 2. The plan of the bodies 2 is represented by dotted lines for better designation.

Oi course, it is possible to empioy sound absorbing bodies having other forms of bases. though the quadratic, at least the rectangular form, and the triangular form are particularly simple and suitable for the assembly of structure.

Another modification of the sound absorbing structure according to the invention is obtained when the sound absorbing bodies the two sound absorbing sets are given unequal heig Further, it is easily possible to provide a st ture in which the two groups ci sound absorcing bodies have diierent angles at the 'tops o pyramids.

An arrangement of this type is shown 5, 'the ground plan o whicis En. Fig. 6. As best shown in Fig. site? f are staggered with relation to the remaining bodies il'. This structure is distinguished a particularly smali sound reverberation, because the shape and arrangement ci the sound absorbing bodies oi the two groups is adapted 'to produce a guiding of the sound energy within the absorbing wall, which is similar to the sound guiding produced by sound absorbing bodies, the side faces of which are concave.

A structure or" the last mentioned kind mai:- ing use of pyramids with concave side surfaces is illlustrated by Fig. 7. The sound absorbing bodies may be arranged as shown in Figs. l and 2. Also by this modification a further, though relatively small improvement of the sound absorbing properties of the structure is obtained.

Sound separating walls, for example such as required between different sound-film studios, are suitably constructed as illustrated by Figs. 8 and 9. Fig. 8 is a section along line 8-8 of Fig. 9. The pyramids of the two groups of sound Fig. 3 is a vertical section taken along absorbing bodies are turned away from one another. Each group of sound absorbing bodies may again be subdivided into several sets which are arranged one behind the other and, preferably, are displaced with respect to one another. Ordinarily, however, it will be useless to provide more than two or three sets.

The height of the cones or pyramids, in all cases, depends on the required sound absorption coeillcient and many be reduced, if the demands are not too high.

A separating wall as represented by Figs. 10 and 1l is particularly advantageous. The ar rangement is a modification of the embodiment shown in Figs. 8 and 9, the solid cones or pyramids being replaced by hollow bodies. Evidently, the effective height of the pyramids oi the one group is increased by the cavities oi the pyramids of the other group, the inner surfaces of the latter being, in a sense, a prolongation or continuation oi' the external surfaces ci the former. The hollows are suitably given a parabolic outline.

In the last mentioned embodiment a plurality oi bodies of each group may be designed to form an integral portion. Similarly, in the above described' cases, a certain number of pyramids or cones, preferably of the same group, may be united to form structural units. The whole sound absorbing structure is then obtained by joining a sufiicient number of such portions or units.

In many cases, especially for constructing a sound absorbing wall according to Figs. l0 and il, it will be convenient to make use of a framework 4a, substantially as illustrated by Fig. l2, to which the slngle (hollow) cones or pyramids are iixed, for example by sewing. Also the above mentioned portions or units may be fastened to a framework.

The sound absorbing bodies preferably consist of tire-proof material, such as glassor slagwool, or of other iire-proofed feltor weddinglike substances. In order to facilitate the form- 1 ing and mounting, the sound absorbing bodies may be covered with or enveloped in a suitable, for example woven, material.

The sound absorbing bodies are fastened to the ceiling of a room preferably by hanging them up by wires. Distortions oi the bodies may be prevented by a net of threads consisting, for ex" ample, of silk.

The above described sound absorbing structures may be used for all purposes where it is desired to obviate rebound or escape oi sound.

Though in the foregoing specification and the accompanying drawings certain specific constructions have been set forth the invention is not limited to the described or illustrated details.

, Various further modifications or changes are possible within the scope of the invention as dedned by specification, drawings, and claims.

I claim: l. A sound absorbing structure made o! interacting members of sound absorbing material, at

y ieast a part of the outer face of said structure being composed of a plurality of tapering elements having individually pointed tops, said elements being arranged in at least two groups, the tops of the elements of each of said groups lying in surfaces substantially parallel, but displaced with respect to one another and a positioning net for each group secured to the tops of the elements of its group.

2. A sound absorbing structure as set forth in claim 1 wherein said tapering elements have the shape of pyramids.

3. A sound absorbing structure made of sound absorbing material, at least a part of the outer face of said structure being composed of a plurality of tapering elements, said elements being arranged in at least two groups, the tops of the elements of each oi' said groups lying in surfaces substantially parallel, but displaced with respect to one another in the direction of the axes of said elements and a positioning net for each group secured to the tops of the elements of its group, the single elements of at least one of said groups being spaced from one another, the elements of every two neighbouring groups being so arranged that the projection of the bases of the elements of the one of said neighbouring groups in the direction of the axes of said elements fills out the spaces between the bases of the elements of the other of said neighbouring groups.

4. A sound absorbing structure made of sound absorbing material, at least a part of the outer face of said structure being composed of a plurality of tapering elements, said elements beins arranged in at least two groups, the pointed ends of all of said elements of said groups beins directed towards the same side of said structure and a positioning net for each group secured to the tops of the elements of its group, the tops of the elements of each of said groups lying in surfaces substantially parallel, but displaced with respect to one another.

5. A sound absorbing structure made of sound absorbing material, at least a part of the outer face of said structure being composed of a plurality of tapering elements, said elements being arranged in at least two groups, the pointed ends of all of said elements of said groups being directed towards the same side of said structure, the tops of the elements of each of said groups lying in surfaces substantially parallel, but displaced with respect to one another in the direction of the axes of said elements to such an extent that at least the surface formed by the bases of the elements of one of said groups substantially coincides with the surface defined by the tops of the elements of one other of said groups.

6. A sound absorbing structure made of sound absorbing material, at least a part of the outer face of said structure being composed of a plurality of tapering elements, said elements being arranged in at least two groups of substan- .tially equal elements, the tops of the elements of each of said groups lying in surfaces substantially parallel, but displaced with respect to one another and a positioning net for each group secured to the tops of the elements of its group. the height of the elements of the one group being different from the height of the elements of at least one other group.

HANNS-HEINZ WOLFF.

l CERTIFICATE oF CORRECTION.-

Patent No. 2.356,61@ v August '2a 191m.

lungs- HEINZ woLFF.

It is hereby certified that error appears in the printed 'specification of the above numbered patent requiring correction'as'followa: `Page 2, first column, line 514., for thev word "alter" read --alternate--fand that the said Letters Patent should be read with this correction therein that the I seme may conform to the record ofhthe caee in the Patent Office.

Signed'and sealed this 28th day of November, A. D. 191414..

Leslie Frazer (Seal) 'Acting Connnissioner of Patents.

. CERTIFICATE 0F CORRECTION.. f Patent No. 2,556,6ho'. August 2a 191m.

Lungsmlm woLFF. A

It is hereby certified that 'error appears in the lprinted. -specification of the above vnumbered patent requiring correction'asfollows: Page 2, first column, line 514 for` theword "alter" red a1ternate; and that the seid Letters Patent "should be read with this correction therein that the same may conform tov the record offthe caes in the 'Patent Office.

signed'ma sealed this 28m day of November, A. D; 191m.

, Leslie Frazer (Seal) r Acting Commissioner of Patents. 

